crazyflyer92

i have already built the gp .25 sized spitfire with a k&b 7.5 df motor plane had been radar at 167 mph flat and level. k&b 7.5 is turning a apc 8.75x9.0 w at 20,000 rpm so now i want to try the big block formula on this gp .25 sized p-47. motor im going to use is a webra speed .61 f.i.r.e on a apc 11x12. lets see if this will even work and will it be fast?

iron eagel

Block off the intake of the cowl other where the cylinder is, if your really looking for it to haul.
Looks cool with that pipe hanging off the back!

airraptor

My Feedback: (66)

I think it will be slower than the 45 sized one lol

MJD

My Feedback: (1)

If it can spin that prop about 13k in the air, may be faster than the 7.5? But that would be a trick I think. No doubt it will move along. I'd make a SWAG of 140 - 145 on that prop, but I could be all wet.

Where is peak power made on that engine I wonder?

airraptor

My Feedback: (66)

what I am getting at is the weight.

crazyflyer92

It should turn over 13,000 in the air i run this motor on an apc 11x8 and turned 15,000 on the ground wont know intill it is done and can put a tach on it and see what it will do.

crazyflyer92

The only reason i went with the webra.61 instead of the k&b 7.5 is because the p47 has a big firewall and i wanted to get more prop out side of the cowl. I could be wrong and this not work but i gotta try it. This webra was in the electric gp proud bird i built 2 the first one broke the wing and the second on the first flight it started moving so fast it flutter the wing and striped the ale servo. Stupid me did not go with metal gear. Oh well live and learn.

crazyflyer92

here is the gp.25 sized spitfire

MJD

My Feedback: (1)

Cool! I snagged a couple of RIRE 7.5's 2-3 years back, in the classifieds, but haven't done anything with them yet. I think I can wedge one into a .25 delta though.

Pond Skipper

The GP Spit looks good I have a OS FX with header and pipe could do the same side mount set up. Did you have any trouble with the balance with the K&B 7.5 on the nose?

crazyflyer92

Those are nice motors! I have one in a diamond dust just did the test flights and break in yesterday plane is really moving! Not even broke in it.

crazyflyer92

No not at all i had to put the battery 2000 mah 4.8v right behind the wing. A little nose heavily but thats the way i like my planes flys great and fast! I also have a bh midget mustang same size .25 with the same motor and its not as fast as the spitfire but pretty close

Axle Al

My Feedback: (25)

yeah I see that little pee wee spitfire!#! I got a moki 1.35 on a phoenix genesis/relentless that will smoke that that little whinny .45............. Big Block!#!#! Kaa-Powwwwwww......winner!!!!

rcguy59

My Feedback: (8)

I had the Spitfire several years ago with a piped OS 32F in it. Radar'd it at a bit over 130, but you could hear aileron flutter on every pass. Couldn't prevent the flutter/buzzing, so I gave up and put a .25FX on it.

crazyflyer92

I did not have that problem with mine i dont know if you used metal gear servos or not? I use the hitec hs 85 mg all the way around i built a new elevator alittle bigger then the stock to make it stronger and got rid of the counter weights on the elevator to eliminate elevator flutter plane is also zap dripped throughout and ale rods are 2-56 with the du-bro black connector. And all ca hinges were change to go Great Planes hinges. Sorry to hear yours flutterd.

crazyflyer92

I see that moki fly! We will race again and i will show you speed!!

Axle Al

My Feedback: (25)

yeah that's right. Didn't the germans use webra's in ww2, the reason they lost LOL Kaa-Pow!

crazyflyer92

You will see what that webra will do!#! Kaa-pow!

Pond Skipper

RCGuy59 how was the speed with the 25FX, was it piped if so what prop combo did you settle with?
I have the header cut at 4.25" and will tune from there.

rcguy59

My Feedback: (8)

The 25FX wasn't piped, just the standard OS muffler. It was still very fast with the .25, but not enough to make the ailerons or elevators buzz. That was the idea behind the .25 in the first place, to only slow it down a bit.

combatpigg

My Feedback: (3)

Would there be enough roll control to use the flaps like ailerons and fix the original ailerons so they are stationary..?.
The "deal breaker" is if there isn't enough roll control to deal with a cross wind, or at landing speed.

rcguy59

My Feedback: (8)

It doesn't have flaps, Chuck. Mine didn't handle very well at low speeds. All it did well was go fast.

airraptor

My Feedback: (66)

The stock GP spitefire with stock OS 25FX and 9x6 prop will hit right at 100 mph straight and level. for a piped 25 FX the 8x7 will be a good prop and should be in the 17,000 range. The spit if properly built up will run right around 180 with a Nelson in it. Stock elevator is only good for around 130 or so and beyond that cant turn hard or it will shear off. Solid tail and then glasses with 1.5 ounce cloth works well

Pond Skipper

Great info thank you Air Raptor, good job I cut the header at 4.25 " I will be very close with a APC 8x7 might try a 7x8 good for around 125 -130.

crazyflyer92

Yes stock elevator is no good for high speed i didnt glass mine just solid tail and no problem had many of flights so far.